SIMULATION OF PINUS-RADIATA ROOT-SYSTEM STRUCTURE FOR ECOSYSTEM MANAGEMENT APPLICATIONS

Pinus radiata forestry is an important industry in New Zealand, and armillaria, a root rot fungus, is a major source of lost timber production. Chemical treatments are largely ineffective and physically removing contaminated material is prohibitively expensive. Biological control techniques give promising indications of effective and ecologically sound management, but the long timescales and concealed systems involved hamper field research. Here the role of simulation in the manipulation and understanding of the ecosystem is examined. The model developed defines a three-dimensional representation of root architecture, which is used as a temporal envelope for simulating root growth. The system then traces the spread of fungal populations along root surfaces. The resulting direct, structural simulation model provides a flexible tool for examining the effects of several factors whose importance is difficult to assess in the field. While there is enormous scope for further development of the system, the current implementation suggests that the model is a useful new approach to understanding the complex soil/root ecosystem. The validation of models of complex but largely random systems is also addressed.